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Appendix VL


P. 709. The Diesel Oil Engine is a stationary engine
of very high economy. Its thermal efficiency on B.H.P. has
reached 28-3 %, while the oil per B.H.P. hour reduces to -4 Ib.
at full load. Moreover, the cheapest form of crude petroleum
can be used as fuel, the average price of which is 455. per ton
delivered, giving one B.H.P. hour for -096^., about half or one-
third of the cost in other oil engines. As in most internal-

F^CfJO2S. TAe Dirictler Gas

combustion motors, the piston acts as compressor on the four-
stroke cycle, and the diagrams in Fig. 1030 shew the operations.
Herr Diesel set out with the intention of adopting the Carnot
cycle, but was .obliged to practically modify the card into (i)
adiabatic compression of air from D to A ; (2) admission of oil
spray at A and combustion at nearly constant pressure from A to B ;